As a result of English experience, Prof. J. Lane Notter, Netley Army Medical School, states that "a prolonged residence in a hot climate doubtless deteriorates the system." Again he says that the great mortality of typhoid in the tropics is because "there is an increased activity in any acute fever due to the diminished resisting power of the individual." "All diseases, however trivial elsewhere, become serious in the tropics," and "the energy of the Anglo-Saxon who has been long resident in the tropics suffers." Lord Roberts noticed the quicker onset of effects of age on the private soldier, and we have found that tuberculosis is rapidly fatal to white men in the tropics.
We have long known that the adult natives of the West Indies, Creoles, etc., did not contract yellow fever, and we believed them to have become immune through acclimatization; but even this is an error, for our yellow fever commission many years ago proved that every one of these "acclimated" natives had had yellow fever in infancy, and were immune from that reason and not from acclimatization. There has been a woeful mortality in New Orleans Creole families from yellow fever in spite of nearly two hundred years of "acclimatization." White residents in the tropics hold to the conviction almost universally that it is no place for whites, and though they insist upon going to a temperate zone for six months every three years, yet even that does not prevent the slow but inevitable deterioration in health.*
Wherever we turn we will find facts which annihilate all our former conceptions of acclimatization, in spite of the fact that in the tropical and subtropical regions of the world there are said to be 10,000,000 of white men living and degenerating. There is even an outcry about South Africa and Australia, which we rather look upon as permanent Anglo-Saxon homes. The London United Service Gazette says: "It is an undoubted fact that the Australasian of two generations is ever on the verge of decadence if new blood is not forthcoming from the mother country. The Anglo-Indian, too, born in that great dependency, though of pure British blood, is very inferior in that energy and virility which mark the Anglo-Saxon race as we know it at home. In South Africa, where at least a better climate is attainable, a stationary population, unfed from home, will certainly degenerate".
Ethnologists, philologists and archaeologists are pretty well agreed as to the fact that existing races and even nations have undergone evolution in climates similar to those in which they now live, and that in spite of being conquered, enslaved, compelled to learn new languages and submit to new civilizations, aborigines may survive their lords and masters, so that in some parts of Europe, such as the French peasants of the Dordogne, the natives are the proved direct pure-blooded descendants of the original inhabitants who have evolved from lower types through untold ages, just where we find them now. Colonizations spread speech, trade and civilization, but not races if they meet adverse climate. Migration resembles glaciers, but speech and civilization are bowlders left in the "terminal moraine" as the glacier melts.
* Kipling, in speaking of his heroine in "William the Conqueror," says: "She stayed down three hot weathers, as her brother was in debt and could not afford the expense of her keep at even a cheap hill station. Therefore, her face was as white as bone." In "The Tomb of His Ancestors," he says: "All India is full of neglected graves that date from the beginning of the eighteenth century- tombs of forgotten colonels of corps long since disbanded; mates of East Indiamen who went on shooting expeditions and never came back; factors, agents, writers, and ensigns of the Honorable, the East India Company, by the hundreds, and thousands and tens of thousands. The English folk forgot quickly".
Of the numerous articles which have been written on the subject of acclimatization, perhaps the best is that by Prof. Wm. Z. Ripley in his "Races of Europe." Its great value consists not only in his high scientific attainments, being our most brilliant anthropologist, but from the fact that he wrote the article before 1896, or long before all such discussion could possibly be accused of having political bias. He says: "To urge the emigration of women, children or of any save those in the most robust health to the tropics, may not be murder in the first degree, but it should be classed, to put mildly, as incitement to it." Doctor Semeleder, of Cordoba, Vera Cruz, says "that white men cannot become acclimatized in the tropics at a less elevation than 3,000 feet, which is a moderate climate." There is a biological law that every 250 feet elevation is equivalent to an advance of one degree of latitude as far as the flora and fauna are concerned. Dr. G. Archdall Reid* also shows that white men can never colonize in malarial parts of the tropics, the change to a new environment being too rapid. The native immunity to malaria is a result of natural selection and the death of the susceptible during untold thousands of years in a gradually changing environment. Doctor Bey fuss in a very temperate article doubts whether life in the tropics is possible for white men even if we exterminate malaria. Mr. Benjamin Kidd is the chief exponent among laymen of the truths of nonacclimatization, and seems to be the pet enemy of all the expansionists-at-any-price. He also shows how evolution in cold climates has produced a far different creature than in the tropics, from which places white men are forever barred as colonists.